The present invention relates to a centrifugally cast, reinforced synthetic resin pole, particularly a pole with a reinforcement comprising a mat permeable by the synthetic resin and having a specific gravity slightly lower than the specific gravity of the synthetic resin and comprising an inner layer of fibers oriented in the longitudinal direction of the pole.
Such poles are commonly encircled at the top end thereof by a pipe-shaped base of a lamp or of a lamp extension arm or by a collar band for clamping the lamp or extension arm to the pole. Where a pipe-shaped base is used, a plurality of equiangularly arranged set screws extend through the base and frictionally abut the pole surface. However, when either a collar band or set screws are used, wind action and the associated swaying at the pole causes the collar band or the set screws to work themselves into the pole, which results in an undesirable wobble or play between the lamp and the pole. Heretofore no practical and economical means have been found to effectively prevent these effects. Consequently it is an object of the present invention to provide a fastening between the pole and the encircling pipe-shaped base that avoids the disadvantages of prior fastening means without incurring excessive cost.
The present invention overcomes the above mentioned disadvantages of prior fastening devices by providing the reinforcement with a layer of flexible wire cloth in the region where the base encircles the pole. The flexible wire cloth layer is especially suited for use in a reinforcement such as that described in our copending U.S. patent application Ser. No. 229,409, filed on Jan. 29, 1981, now U.S. Pat. No. 4,383,965 entitled "Centrifugal Process For The Production Of A Pipe-shaped Body And A Pipe-shaped Body Produced According To The Centrifugal Process," the disclosure of which is hereby incorporated herein by reference. The special reinforcement disclosed therein insures that the inner layer of fibers will not penetrate to the surface, but rather will stay well within the pole wall. During the manufacture of a pole with such a reinforcement, the resin sprayed into the rotating mold penetrates the reinforcement, and particularly its outer resin penetrable mat layer, such that the mat floats on the resin due to the lower specific gravity of the resin. If a woven wire cloth is embedded in this reinforcement, it also will float with the mat, and will stay well within the pole wall. When the synthetic resin hardens, the woven wire cloth serves as a substantially impenetrable reinforcement for the pole. When the collar band or set screws are tightened, they penetrate only the outermost surface layer of the hardened synthetic resin and then strike the woven wire, where they not only encounter solid resistance, but also find a sort of anchoring. Thus, the woven wire cloth prevents the collar band or set screws from working themselves any further into the pole and wobbling or play between the lamp and the pole is eliminated.
It is contemplated that the length of the woven wire cloth is slightly less then the circumference of the outside surface of the pole at its top end such that the ends of the cloth just meet in its floated position. However, the wire preferably consists of strong, rust-proof metal such as stainless steel. The rust-proof property is especially important because the cloth may be exposed to some rainwater and air when the collar band or set screws abut the cloth.
Other features which are considered characteristic of the invention are set forth in the appended claims.
Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.